drader



April 28, 1942. J. c. DRADER BUILT-UP ABRAS IVE Filed April 15, 1936Mill! lllllll mm 1 H INVENTOR.

735.9 [1' flrdd Patented Apr. 28, 1942 u r sa Ei i'l OFFICE BUKLT-UPABRASIVE Joseph C. Drader, Detroit, Mich, assignor to Michigan ToolCompany, a corporation of Delaware 1 Claim.

The present invention relates to gear finishing tools, and in particularprovides an improved finishing tool having teeth of composite form.

The co-pending application of Paul F. Seibold, Serial No. 58,838, filedJanuary 13, 1936, discloses an improved method and machine for finishinggears and other objects which, in its application to gear finishing, maybe characterized as providing means for supporting a gear and afinishing tool in mating relation, rapidly reciprocating the toolrelative to the gear in a path parallel to the tooth faces of the gear,and relatively slowly rolling the gear relative to the tool. Due to therelatively high ratio between the rate of reciprocation and the rate ofrolling, all or substantially all of the finishing action isaccomplished by the reciprocation. The tool teeth are preferably formedconjugate to the gear teeth and the improved method produces gearshaving teeth of accurate form, the deformation commonly produced inconventional gear finishing methods due to the roll of the gear and toolbeing substantially if not entirely eliminated.

Objects of the present invention are to provide an improved finishingtool, particularly suited for the practice of the invention disclosed inthe above identified Seibold application, but also well suited for thepractice of other gear finishing methods; to provide such a tool whichis of composite form, embodying abrasive elements adhered to backingmembers, the abrasive elements being preformed to conform to the desiredresultant gear tooth form; to provide such a tool in which the abrasiveelements and backing members are rabbeted together; to provide such atool in which the rabbet joint between the abrasive elements and thebacking members extends substantially parallel to the pitch surface ofthe tool; to provide such a tool in which the rabbet joint between theabrasive elements and the backing members may extend substantiallyperpendicular to the pitch surface of the tool; to provide such a toolembodying Wedge means to retain the abrasive elements and backingmembers in assembled relation; and to provide a tool construction whichmay be embodied in either a tool of the circular or gearlike type or ofthe rack type.

With the above and other objects in view which appear in the followingdescription and in the appended claim, preferred but illustrativeembodiments of the present invention are shown in the accompanyingdrawing, throughout the several views of which corresponding referencecharacters are used to designate corresponding parts, and in which:

Figure l is a top plan View of a rack embodying the present invention;

Figure 2 is a fragmentary view in vertical section, taken along the line2-2 of Figure 1;

Figure 3 is a fragmentary view in vertical section of a modified rackconstruction;

Figure 4 is a view in elevation showing an em bodiment of the inventionin a tool of the gearlike type;

Figures 5, 6 and '7 are views illustrating a rabbeted construction;

Figures 8 and 9 are views illustrating a modified rabbeted construction;

Figures 10 and 11 are views of a further modified rabbeted construction;

Figure 12 is a fragmentary View illustrating a wedge construction; and

Figure 13 is a fragmentary view of a modified wedge construction.

Referring first to Figures 1 and 2, the illustration rack constructioncomprises a base member 20 having a longitudinally extending recessdefined by the side walls 22, within which a plurality of rack blades 24and 26 are disposed, and are secured in place in abutting relation bythe bolt 28 which passes longitudinally through the blades and the nuts30 associated with which bear against the end walls 32 of the recess.

In accordance with the disclosure of the above identified Seiboldapplication, the initial group of rack blades 24 are preferably ofconventional construction, having the upper portions thereof tapered toform rack teeth 34 of form conjugate to that which it is desired toproduce on the gear to be finished. These teeth serve, in operation, toinitially position the gear relative to the rack.

The remaining blades 25 are, in accordance with the present invention,of composite form, and embody abrasive sticks 35 and steel backingmembers 38. The abrasive sticks are tapered in their upper portions toform teeth of form similar to the teeth 3t, and conjugate to the desiredgear teeth. The bases 49 of the abrasive sticks are V or wedge-shapedand mate with corresponding V-shaped recesses formed in the backingmembers 38. The abrasive elements 36 and the back- 1 ing members 38 arefirmly bonded together along the surfaces provided by the wedges and V-shaped recesses. The bonding may be effected in various ways, the exactadhesive or other bonding material utilized forming no part of thepresent invention.

In the modified ccnstruction shown in Figure 3, the separate backingmembers 38 of Figure 2 are replaced by a single backing member 42provided with a plurality of successively disposed and parallel V-shapedrecesses it to receive the abrasive elements 38. Similarly, the separateblades 24 are replaced by a single member 46, having the plurality ofrack teeth 34 formed thereon.

In the embodiment shown in Figure 4, the

tool 50 is of the circular or gear-like type, and comprises the circularbody portion having a plurality of V-shaped recesses 52 formed in theperiphery thereof, each adapted to receive an abrasive tooth portion 54of form conjugate to that which it is desired to produce on the gear.The abrasive elements 54 are bonded to the body of the tool in themanner described with reference to Figures 2 and 3.

In certain instances it is desirable to replace or supplement theadhesive bond between the abrasive elements and the backing members. Inthe embodiment of Figures 5, 6 and '7, this is accomplished by formingrabbet joints between the abrasive elements 60 and the backing members62. Each rabbet joint is illustrated as extending substantially parallelto the pitch surface of the tool, and as being provided by theoppositely directed but similar rabbets 64 in each abrasive element andcorresponding anchors or tongues 66 in each backing element. Inassembly, each abrasive element and its corresponding backing member isdisposed in end to end relation with the rabbet elements in registrywith each other, and are then slid together. Retaining plates 68,secured to the backing members 62 by studs 10 are preferably provided topositively retain the abrasive elements and backing members againstrelative longitudinal movement.

In the just described construction, the longitudinally extending rabbetjoints are particularly effective in withstanding stresses to which theabrasive elements are subjected due to the roll of the gear. In certainother instances, it is considered desirable to form a joint between theabrasive elements and the backing members so as to be particularlyeifective in withstanding the stresses to which the abrasive elementsare subjected due to the lateral reciprocation be tween the gear and thefinishing tool. In Figures 8 and 9, this is accomplished by disposingthe rabbet joints substantially perpendicular to the direction ofrelative reciprocation between the finishing tool and the gear. Asillustrated, each abrasive element 80 is provided on its inner surfacewith a plurality of spaced lands and grooves 82, which mate withcorresponding lands and grooves 84 formed in the V-shaped recess 86 ofthe backing member 88. Preferably, a bond as described with reference toFigures 1, 2 and 3, is provided to adhere each abrasive element 80 tothe associated backing member 88 in order to withstand the stresses onthe abrasive element due to the roll of the gear and tool,

Figures 10 and 11 illustrate a construction similar in many respects tothe construction described with reference to Figures 5, 6 and '7 inwhich the single rabbet 54 of Figures 5, 6 and 7 is replaced by aplurality of longitudinally extending serrations 90 formed in eachabrasive element 92, and which mate with corresponding longitudinallyextending serrations 94 formed in the associated backing member 96. Endplates 98 secured to the backing members 96 by studs I are preferablyprovided to positively prevent relative longitudinal movement betweenthe parts. As in the previously described embodiments, the union thusformed between the abrasive elements and the backing members may replaceor supplement any adhesive bond formed therebetween.

In the embodiments of Figures 12 and 13, wedges are utilized to replaceor supplement adhesive bonds between the abrasive elements and thebacking members. In Figure 12, the abrasive elements III] are providedwith V-shaped bases I [2 as described with reference to the otherembodiments and in addition, are provided with longitudinally extendinglaterally disposed shoulders H4, against which the longitudinallyextending locking strips H6 bear. The locking strips H6 may be securedto the tool structure in various ways, as by side bars I24 which engagethe hooked ends of the strips. In Figure 13, the shoulders H4 andlocking strips H6 of Figure 12 are dispensed with and are replaced byV-shaped wedge members H8, the tapered sides of which mate with and bearagainst the corresponding tapered sides of the abrasive elements I20 andthus positively force the latter into engagement with the backingmembers I22.

In each of the foregoing embodiments, it will be observed that each tooltooth is of composite construction, embodying an abrasive element and ametallic backing member, which are suitably bonded together. The use ofthe solid abrasive sticks effectively overcome any difiicultiesheretofore encountered through application of abrasive layers to thetooth portions of the rack or tool blades. The combination of theabrasive sticks with the metallic backing members effectively overcomesany difiiculty which might otherwise be encountered due to thesubstantial compressive force to which it is necessary to subject theblades by the securing bolt 28, to hold the blades in proper relativeposition. The resulting tool is accordingly highly effective andsatisfactory in operation and as will be evident from the simpleconstruction of the elements thereof, may be relatively economicallyproduced.

In practice, it will be appreciated that the expected duty of the toolwill determine whether the abrasive elements and the backing members areto be secured together entirely by an adhesive bond, or whethermechanical anchoring means will be provided between the abrasiveelements and backing members. The same considerations will alsodetermine whether the mechanical or adhesive bonds are to be usedseparately or in supplementary relation. The adhesive bond isadvantageous in that it permits a simpler formation of the individualelements, while the mechanical bond is regarded as advisable for heavierduty application of the tool.

Although only a few embodiments of the present invention have beendescribed in detail, it will be evident that various modifications inthe form and arrangement of the parts of the illustrated embodiments maybe made within the spirit of the present invention. The describedembodiments, accordingly, are to be regarded in an illustrative and notin a limiting sense.

What is claimed is:

A tool for finishing gears or the like having a body portion and aplurality of teeth formed thereon, each of said teeth comprising asingle abrasive element of a form conjugate to the teeth to be produced,each of said abrasive elements and said body portion having a pluralityof mating serrations extending along the cooperating surfaces thereof toform an interlocking joint therebetween.

JOSEPH C. DRADER.

